Probabilistic safety assessment of the French PWR 900 Mwe series. Results and insights

F. Corenwinder, V. Bertrand, P. Dupuy, C. Gomane, J.M. Mattéi, F. Pichereau, PSAM6 conference, Puerto Rico, juin 2002, Rapport IRSN-DES/517

The Institute for Nuclear Safety and Protection (IRSN) has been performing an updating of the Probabilistic Safety Assessment of the standard French 900 MWe PWR in order to include design and operation modifications set up since the first version of this study published by IRSN in 1990. Moreover the updating takes into account new data and new knowledge. For these reasons many sequences have been reassessed and new sequences have been identified. The updating has highlighted significant accident sequences (cold over pressurization, interfacing LOCA, loss of ventilation systems and inadvertent dilution), which were not included or not analyzed in details in the first PSA version. Moreover, the update has allowed the verification of the design and operational changes implemented to decrease the frequencies of the dominant accident sequences identified by the 1990 PSA study. The purpose of the paper is to describe the dominant accident sequences and to present the main significant points of the analysis, the main insights and the conclusions.